Additive filter



ADDITIVE FILTER Filed Jan. 28, 1964 2 Sheets-Sheet 1- F/L rm FA BRICAT/NG MACH/NE if m; m X a Mo SPREAD/N6 0R w/va OVEN 4 DEV/(2E 5L URR) TANK TOP ROLL wSPREAD FILTER TOW GEORGE P. TOUEY JOHN E. K/EFER INVENTORS' March 28, 1967 p, TOUEY ET AL 3,311,519

ADDITIVE FILTER Filed Jan. 28, 1964 2 Sheets-Sheet 2 8L URRY TANK SPREAD FILTER TOM TOP ROLL BOTTOM ROLL TOW W/TH ADO/T/VE F/LAMENTS w/ TH 1100/7/ v5 FIG. 5.

FIG. 4.

TREATED F/LAME/VT MAfER/AL GEORGE P. TOUEY JOHN E. K/EFER INVENTORS BY Q.

ATTORNEYS United States Patent 3,311,519 ADDITIVE FILTER George Patrick Touey and John Edward Kiefer, Kingsport, Tenn., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Filed Jan. 28, 1%4, Ser. No. 340,601 3 Claims. (Cl. 156180) This invention relates to tobacco smoke filters. More particularly, this invention concerns method and apparatus for producing a tobacco smoke filter containing finely divided carbon.

In U.S. Patent 2,881,770 to Touey are disclosed fibrous tobacco smoke filters carrying finely divided carbon particles on the surface of the filaments thereof. In U.S. Patent 3,043,736 Touey discloses applying carbon powder to opened and banded moving tow as a latex emulsion or slurry in aqueous media, in a volatile organic vehicle or in a plasticizer. More recently, to alleviate the possibility of some of the carbon reaching the smokers mouth and for other purposes, dual filters have been developed in which two or more filters are use-d, the one next to the smokers mouth containing no carbon.

While this latter, dual, arrangement has proved successful in its purpose of minimizing possible drawing or pulling of particles of carbon into the smokers mouth, it calls for added expense and time involved in handling and storing two different types of filters, one treated and the other untreated and accordingly tends to increase any complications which may arise in fabrication of finished filters. It is therefore apparent that development of a way of making a filter substantially free of carbon particles in one zone susceptible of escape into the cigarette smokers mouth represents a highly desirable result. After extended experimentation we have devised a convenient and economical apparatus and method of producing a carbon-containing filter element whereby chance of drawing of carbon into the smokers mouth is minimized.

It is an object of our invention to provide process and apparatus for producing a carbon-additive filter element. Another object is to provide simple and inexpensive means for producing a one-piece filter element made of tow treated with carbon in certain areas only whereby possibility of passage of carbon particles into the smokers mouth is substantially eliminated. Further objects will be apparent hereinafter.

In its broader aspects our invention involves applying to alternating portions of moving handed and opened filter tow a liquid dispersion of finely divided additive such as activated carbon and forming the thus treated tow into unitary rod-shaped filter elements each of which contains both a portion with additive and a portion without additive. The resulting filter elements are each in one piece with no segment or division between the treated and non-treated portions except a visible reasonably clear-cut dividing line, such as the difference between black and white portion in the case of cellulose acetate filter rods containing activated carbon.

Any textile tow which is suitable for making cigarette filter tips may be used in carrying out this invention. Tows made from cellulose esters, regenerated cellulose, cotton, polyolefins such as polyethylene and polypropylene, and other synthetic fibers may be used. Crimped tow such as those described in U.S. Patents 3,017,309, 2,794,239, 2,966,157 and 3,038,478 to Touey or coworkers are particularly useful.

Media which we have found useful in applying the additive to a filter tow according to our invention consists of at least one liquid vehicle for dispersing the additive, and

a suspending agent. A bonding agent may be used with or in place of water as the liquid vehicle which serves as 3,311,519 Patented Mar. 28, 1967 the bonding agent for binding the additive to the tow fibers.

The carbon may be derived from wood, petroleum, nut shell such as cocoanut or pecan shell, coal, blood, bone, or other convenient sources. It should have a particle size which would allow it to pass through a 40 mesh screen.

Water is a convenient liquid vehicle since it is readily available and need not be recovered. The suspending agent and bonding agent may be the same material. Cellulose derivatives such as carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, sodium cellulose sulfate and cellulose monoand diacetates; vinyl polymers such as poly(vinyl chloride), poly(vinyl alcohol), poly- (vinyl acetate), poly(vinylpyrrolidone), and sodium stymer; natural gums such as gum arabic; casein; alginates; gelatin, dextrin, and the modified and unmodified starches may be used.

According to one embodiment of our invention the carbon additive is applied to alternate areas of the spreadout tow by pulling the tow through a pair of rotating cogwheels so mated that the outer circumference of cogs of the lower roll apply additive such as dispersed carbon at regular intervals along the length of the moving tow from a liquid bath in which the lower roll is at least partially immersed as it rotates, the upper roll rotating in the opposite direction.

In another embodiment the carbon dispersion may be applied by stamping alternate sections of tow with a sponge containing said dispersion. In either instance the treated tow is cured or dried and then cut at regular intervals alternating between the center of carbon treated and untreated sections such that each rod has an untreated section to be used as the part placed next to the smokers mouth. Thus the treated segment of the unitary rod need not contact the smokers mouth.

For a further understanding of our invention reference is made to the drawing in which:

FIG. 1 is a semi-schematic representation of the tow treating method and apparatus of our invention.

FIG. 2 is an enlarged view of the tow treating portion of our invention showing the rolls and tow treating means as they appear in perspective from the end.

FIG. 3 is a top view of the tow-treating means of our invention.

LFIG. 4 depicts a section of filter t-ow treated in alternate portions and fabricated into rod-shaped form as it appears prior to cutting into individual filter elements.

FIG. 5 is an enlarged view showing the alternating treated and untreated portions of the filaments of a section of tow.

Looking now at the drawing, the tow 10 is spread out in spreading device 12 to form. a band 14 about 6 inches in width, then pulled through a pair of cog wheels 16 and 18 mated so that the outer circumference of the cogs contact the tow at regular intervals. We have obtained good results with the outer circumference of the cogs coated with rubber or sponge material. A reservoir 20 of the carbon slurry is positioned so that the cogs 22 from the lower wheel 18 will dip into the slurry 24, and as the cogwheels 16 and 18 revolve, the outer circumference of both cogwheels becomes saturated with the carbon slurry. The outer circumference of the upper wheel obtains a uniform saturation of carbon slurry by seepage between filaments of the tow. However, if desired, carbon slurry may also be applied to the upper wheel cogs from a wick or minutely perforated bottom of a slurry tank placed above the upper wheel.

As the tow 14 passes between the wheels 16 and 18, it adsorbs the slurry from the surface of the cogs and a tow 26 containing alternate bands of untreated and treated areas is obtained. The tow is then passed through a dryer 28 and into a filter fabricating machine 30. As the continuous shaped tow 32 emerges from the machine 30, it may be cut by a cutter (not shown) into filter rods of any desired length. The rods may be cut again prior to attaching to cigarettes. The cutting should be done approximately in the center of the carbon treated band and the center of the untreated band. Thus, the final filter tips will have a length of carbon treated filter which is approximately one half the cog treating distance a in FIG. 1. Each tip will also have a length of untreated filter approximately one half the non-cog treating distance b in FIG. 1.

For a further understanding of our invention the following examples are presented as illustrative thereof.

EXAMPLE I 'Iwo applicators were prepared as follows. A cellulose sponge was cut into strips 20 mm. x 20 mm. x 150 mm. Ten of the strips were suitably adhered onto a glass plate which was 150 mm. wide and 400 mm. long. The pieces of sponge were positioned on the glass so that they were 20 mm. apart and parallel to each other.

The sponges on the 2 applicators (a total of 20 sponges) were saturated with a slurry consisting of 14% by weight activated carbon (obtained from the American Norit Corn pany under the trade name of Norit SS), 2% methyl cellulose, and 84% water.

A tow of cellulose acetate yarn containing approximately 12,000 crimped fibers of 5 denier per filament was spread out to a width of about 140 mm. The spread tow was laid on one of the applicators so that the longitudinal direction of the tow was at right angles to the long dimension of the sponges. The second applicator was then laid on top of the tow in such a way that the sponges on the top applicators were directly above the sponges on the bottom applicator. The applicators were removed and the tow was dried. The tow prepared in this manner had alternate bands of carbon coated fibers and uncoated fibers. The coated and uncoated bands were each about 20 mm. wide.

The treated tow was bundled together and pulled through a cigarette filter make-up machine which wrapped the tow with paper. The filter rod which contained 20 mm. sections of carbon coated tow separated by 20 mm. sections of untreated tow was cut into 20 mm. filter tips. The cuts were made in the center of the carbon section, and the center of the untreated section. Approximately one half of each filter tip contained carbon. The filter tips were attached to a standard king size cigarette by means of a cellophane tape. The end of the filter which contained the carbon was placed next to the tobacco of the cigarette. The cigarettes were then smoked with an automatic smoking device. The vapor phase of the smoke which exited from the filter was collected and analyzed by gas chromatography. The amounts of several components of this gas phase are listed in the following table. The amounts of the same components found in unfiltered smoke are also listed for camparison.

11g. Found in g. Found in A tow of polypropylene containing approximately 15, 00 crimped fibers of 3 denier per filament was spread out and treated with carbon by the method described in Example I. The filter types prepared from the tow consisted of mm. of carbon treated tow and 10 mm. of untreated tow.

4 EXAMPLE In A tow of cellulose acetate yarn containing 6,000 crimped fibers of 8 denier per filament was spread out to a width of 6 inches and pulled between 2 rotating cogwheels which were aligned as shown in FIG. 1. The peripheral surfaces of the cogs were coated with a spongy absorbent material. The distances at and b were both 10 mm. The carbon slurry tank contained a slurry consisting of 28% activated carbon (powdered cocoanut shell carbon No. 495 obtained from Barnebey-Cheney Company), 4% methyl cellulose and 68% water. As the tow exited from the cogwheels it was passed through a drying oven to remove the water, then into a filter fabricating machine. The continuous filter rod which was ejected from the machine contained alternate sections of carbon treated fibers and untreated fibers. The rod was cut approximately in the center of each carbon section and approximately in the center of each untreated section. The resulting filter tips were 20 mm. long and contained a carbon section approximately 10 mm. long and an untreated section approximately 10 mm. long.

EXAMPLE IV This example demonstrates how the cogged wheel applicator would work on a larger scale in depositing additive on alternating segments of filter tow according to our invention.

The peripheral circumferential surfaces of the cogs of upper and lower wheels consist of cellulose sponge onequarter /4) inch in thickness. However, other absorbent material such as sponge rubber or the like resilient substance may be used with equal efiiciency. The wheels turn such that the cogs meet at nip as indicated generally in FIG. 1. The major circumference of the cogwheel was 37.6 inches and the minor circumference was 31.4 inches. The individual peripheral surfaces of the cogs were 0.4 inch along the arc of the circle formed thereby and the width of the flats at the root of the cogs was 0.27 inch. The total length of the cogwheel was 14 inches. The shaft of the lower wheel is fitted via hearings to turning mean-s (not shown) and driven by an electric motor (not shown). The upper wheel is synchronize-d in harmony with the lower wheel, both having driven by a common drive (not shown). As the lower wheel rotates counterclockwise and the upper clockwise their cogs or teeth meet and draw an eight inch wide band of crimped continuous filament cellulose acetate tow of 8 denier per filament and 48,000 total denier through the nip formed by the meeting sponge-coated cogs. A dispersion of 16% activated carbon, 3% methyl cellulose and 81% water adheres to the absorbent cog surfaces as the lower wheel turns such that it cogs dip about one-half /2) inch into the dispersion held in a tank about 12 inches by 18 inches by 6 inches in size and made of stainless steel. For the first few feet the under side of the tow picks up the liquid dispersion of carbon at alternating intervals the distance apart of the rotating peripheral surfaces of the cogs containing the carbon dispersion absorbed thereon. After the first few turns of the wheels sufficient carbon dispersion is absorbed on the lower-wheel cogs for enough to remain after some is deposited at the regular intervals on the under side of the moving tow to penetrate between the tow filaments and be absorbed on the spongy outer surfaces of the upper wheel cogs and then pass therefrom and be deposited at the same regular intervals on the top side of the tow. The tow passes continuously from the treating step to a garniture for fabricating into rod-like form, the compacted and wrapped tow then being cut regularly at the respective midpoints of treated and untreated portions. The resulting filter elements are then attached to standard brand cigarettes reduced in size to allow for attachment of filter sections such that the carbon containing portions are away from the smoking end and smoked on a cigarette-smoking machine. The cigarettes thus smoked prove highly eifective in tar and nicotine removal.

From the preceding description and examples it should be evident that we have provided simple and economical means for producing one-piece cylindrical-shaped tobacco smoke filter elements containing additive only on the portions of said elements positioned away from the smokers mouth.

Although the invention has been described in considerable detail with particular reference to certain preferred embodiments thereof, variations and modifications can be efiected within the spirit and scope of the invention as described herein, and as defined in the appended claims.

We claim:

1. The method of treating continuous filament tow which comprises applying activated carbon to alternate sections of a single band of continuous filament tow of at least about 6000 filaments arranged in a generally parallel relationship to the longitudinal axis of the tow and of a denier per filament of about 3 to 8 from an aqueous dispersion of the activated carbon by striking said alternate sections of the tow with corresponding alternate prot-rusions of the lower roll of a pair of rotating rolls as the tow passes through the nip formed therebetween, forming the tow with activated carbon thus applied thereto into substantially cylindrical wrapped filter rods, and cutting said rods so as to form filter elements containing the activated carbon deposited on alternate sections thereof.

2. A method of claim 1 wherein the dispersion of ad di-tive comprises 12-30% by weight activated carbon, 15 by weight methyl cellulose and the remainder water.

3. The method of claim 1 wherein said rods are cut at approximately the midpoint thereof.

References Cited by the Examiner UNITED STATES PATENTS 928,631 7/1909 Costikyan 1 1l8-121 941,530 11/1911 McKibbin 118-12 1 1,488,299 2/ 1923 Thomayer 68-202 2,166,740 7/1939 Karpius 16l--174 2,612,679 10/1952 Ladisch 161--174 2,881,770 4/1959 Touey 131208 2,915,069 1 2/1959 Schur. 2,940,456 6/1960 Touey 131208 2,966,157 12/1960 Touey et a1. 13 l208 3,021,242 2/1962 Touey 156-180 3,026,226 3/1962 Touey et al 156--180 3,043,736 7/1962 Touey 156l52 FOREIGN PATENTS 36,247 9/ 1935 Netherlands.

OTHER REFERENCES The Condensed Chemical Dictionary, p. 735, 6th edition, published 1961 by Reinhold Publishing Corp, New York.

EARL M. BERGERT, Primary Examiner.

F. RAY CHAPPELL, ALEXANDER WYMAN,

Examiners. R. A. FLORES, Assistant Examiner. 

1. THE METHOD OF TREATING CONTINUOUS FILAMENT TOW WHICH COMPRISES APPLYING ACTIVATED CARBON TO ALTERNATE SECTIONS OF A SINGLE BAND OF CONTINUOUS FILAMENT TOW OF AT LEAST ABOUT 6000 FILAMENTS ARRANGED IN A GENERALLY PARALLEL RELATIONSHIP TO THE LONGITUDINAL AXIS OF THE TOW AND OF A DENIER PER FILAMENT OF ABOUT 3 TO 8 FROM AN AQUEOUS DISPERSION OF THE ACTIVATED CARBON BY STRIKING SAID ALTERNATE SECTIONS OF THE TOW WITH CORRESPONDING ALTERNATE PROTRUSIONS OF THE LOWER ROLL OF A PAIR OF ROTATING ROLLS AS THE TOW PASSES THROUGH THE NIP FORMED THEREBETWEEN, FORMING THE TOW WITH ACTIVATED CARBON THUS APPLIED THERETO INTO SUBSTANTIALLY CYLINDRICAL WRAPPED FILTER RODS, AND CUTTING SAID RODS SO AS TO FORM FILTER ELEMENTS CONTAINING THE ACTIVATED CARBON DEPOSITED ON ALTENATE SECTIONS THEREOF. 